1. Field of Invention
The present invention relates to an integrated circuit of an internal voltage generator. More particularly, the present invention relates to a two phase internal voltage generator providing low current consumption, which is adapted to low-power integrated circuit.
2. Description of Related Art
As scientific technology advances and environmental consciousness awakens, integrated circuitry proceeds towards high speed operation and low power consumption accordingly. Therefore, power saving and size reducing scheme as well as enhanced functions are thus introduced to varieties of electronic products. It is a major object to substantially realize low power consumption for Integrated Circuits (IC), for example, low power consumption Dynamic Random Access Memory (DRAM). Undoubtedly, low power scheme is particularly significant for Personal Computer (PC) market as well as consumer electronics market.
FIG. 1 illustrates a circuit of a conventional internal voltage generator. The conventional internal voltage generator is for generating and providing steady and regulated internal voltage source, where the internal voltage source VINT is different from an external voltage source VEXT. The external voltage source varies within the range from 2.3V to 2.7 V while the internal voltage VINT is fixed at 2.1V, for example.
Referring to FIG. 1, the internal voltage generator 10 comprises a comparator 12, an NMOS power transistor 14, a resistor R1 and another resistor R2. It is known from FIG. 1 that the internal voltage generator 10 comprises a feedback loop, wherein resistors R1 and R2 serves as a voltage divider for internal voltage VINT and feeds the divided voltage back to the comparator 12. Comparison between the feedback voltage and reference voltage vREFDC performed by comparator 12 hereby controls the NMOS power transistor 14 so as to obtain the internal voltage VINT.
In this conventional internal voltage generator 10, the resistors R1 and R2 are serially connected wherein the two ends of each resistor couple to the internal voltage and ground respectively, thus considerable direct current (dc current) is consumed thereby, i.e. significant dc current is consumed under active mode. Assuming the internal voltage generator applying to DRAM and the active dc current being 600 μA, as the DRAM operates a self refresh, there is supposed to be 8 internal voltage generator operating simultaneously, such that an average active dc current is: 30 μA=(600 μA*8*100 nS)/16 μS, where power consumption is considerably large, which means such IC is hardly referred as a low power consumption IC that conventional internal voltage generator 10 does not qualify a low power consumption IC.